Rapid and highly sensitive detection of Salmonella Typhimurium in lettuce by using magnetic fluorescent nanoparticles
The high-efficiency detection of Salmonella Typhimurium (S. Typhimurium), a common foodborne bacterial, is important for leafy vegetables safety assurance. In this study, a fluorescent sensor (FMNCs-Apt), based on Fe3O4 magnetic nanoparticles and aptamer-modified carbon quantum dots, was developed for rapid and highly sensitive detection of S. Typhimurium in lettuce. First, carbon quantum dots were covalently bonded to the surface of prepared Fe3O4@chitosan to form magnetic fluorescence composite nanoparticles (FMNCs). Then, the aptamers of S. Typhimurium were covalently linked to the surface FMNCs-Apt. Fluorescence intensity of the FMNCs-Apt probes decreased as they aggregated on the surface of bacterial and the aggregation was separated using a magnet. Under the optimal conditions, the fluorescence change values of the solution were shown a good linear relationship with the concentration of Salmonella (103 - 106 cfu·mL-1). The detection limit of the method is 100 cfu·mL-1 and 138 cfu·mL-1 in fresh-cut vegetables washing solution and lettuce sample respectively. Accordingly, this developed fluorescent probe became a highly sensitive and efficient sensor for rapid detection of S. Typhimurium in lettuce.